The present invention relates to a liquid supplying system for supply liquid to outside with a negative pressure, more particularly, a liquid supplying system and a liquid supply container in which a remaining amount of the liquid in a liquid containing portion.
Heretofore, in a field of ink jet recording apparatus, for example, a liquid supply method for supplying the liquid part with negative pressure, is used in an ink container which is integral with a recording head. The head cartridge is classified into a type in which the recording head and the ink container (ink accommodating portion) are normally integral and a type in which the recording means and the ink reservoir portion are separate parts both of which are separable from the recording device, respectively and are integral in use.
One of the easiest ways of supplying the liquid with negative pressure is the use of a capillary force of a porous material. The ink container using the method includes a porous material such as sponge accommodated or preferably compressed and accommodated in the entirety of the ink container, an air vent capable of introducing air into the ink reservoir portion to permit smooth ink supply during printing. However, the use of the porous member as an ink retaining member involves a problem that ink accommodating efficiency per unit volume is low. In order to solve this problem, EP0580433 which has been assigned to assignee of the present application has proposed an ink container comprising a negative pressure producing member accommodating chamber and an ink reservoir chamber which is substantially sealed except for a communicating portion therebetween, and the negative pressure producing member accommodating chamber is open to the ambience or atmosphere. In EP0581531, a proposal has been made in which the ink reservoir chamber is exchangeable. With such a structure, when the container becomes empty, only the ink reservoir chamber is exchanged, so that amount of waste can be reduced, which is advantageous in terms of environmental health.
In this ink container, the ink is supplied from the ink reservoir chamber into the negative pressure producing member accommodating chamber with gas-liquid exchanging operation involving introduction of the gas into the ink reservoir chamber with a discharge of the ink from the ink reservoir chamber, and therefore, the ink can be supplied out with substantially constant negative pressure when the gas-liquid exchanging operation occurs.
EP0738605 which has been assigned to the assignee of the present application has proposed a liquid container including a substantially prism configuration casing, and an accommodating portion deformable with discharge of the liquid accommodated and having an outer surface which is similar or equivalent to the inner surface of the casing, wherein the thickness of the accommodating portion is such that it is thinner at corner portion than at the central region at each side of the substantially prism configuration. The liquid container is able to supply the liquid with a negative pressure by proper contraction of the accommodating portion with discharge of the liquid (without gas-liquid exchange in the phenomenon). Therefore, the limitation to the location of the container is smaller than a conventional bladder type ink reservoir member, and can be disposed on a carriage. Since the ink is directly accommodated in the accommodating portion, the ink accommodating efficiency is improved. As mentioned above, the liquid supplying system including the negative pressure producing member accommodating chamber and the ink reservoir chamber is good in the improvement of the ink accommodating efficiency and the stability of the ink supply property, and particularly the type in which ink reservoir chamber is exchangeable is good in terms of the environmental health.
However, in the conventional gas-liquid exchanging operation, the ink discharge from the ink reservoir chamber into the negative pressure producing member accommodating chamber is interrelated with the introduction of the ambience through the communicating portion, and therefore, when a large amount of the ink is to be discharged in a short time from the negative pressure producing member accommodating chamber to the outside such as liquid ejecting head, for example, there is a liability at the ink supply from the ink reservoir chamber into the negative pressure producing member accommodating chamber involving the gas-liquid exchanging operation is not sufficient relative to the high rate ink consumption from the negative pressure producing member accommodating chamber. Therefore, in order to solve the problem of the insufficient ink supply, the state in the ink reservoir chamber is important.
As for a method for detecting reduction of the ink remaining amount or the ink remaining amount per se, there is a system in which two electrodes are provided in the ink container, and an electric resistance or the conduction state between the electrodes is detected. In another method, the ink container is made of a light-transmissive material, and an optical sensor is disposed adjacent the ink container to detect the amount of the light transmitted through the ink container.
However, in the type using the electrodes in the ink container, when the ink container is exchanged (exchangeable type), the parts concerned with a detecting means such as electrodes or the like provided in the ink container have to be exchanged with the result of increase of the manufacturing cost of the ink container and increase of the running cost. In the method detecting the quantity of light passing through the ink container, the erroneous detection tends to occur for the light ink such as yellow ink.
In order to solve the program, Japanese Laid-open Patent Application No. HEI 10-109430 has proposed that first electrode is provided in the recording head, and a second electrode of non-contact type is disposed adjacent the ink container without contacting to the ink container, in which a pulse voltage is applied to the first electrode, and the voltage produced at the second electrode is detected, on the basis of which the remaining amount of the ink in the ink container is detected. In the detection system, the input signal to the first electrode is transmitted through the ink from the recording head to the ink container, and a detection signal is obtained on the basis of the capacitive coupling between the ink container and the second electrode.
In the above-described without, the electrostatic capacity provided by the capacitive coupling changes in accordance with an area of the second electrode opposed to the ink. Therefore, if the ink remains in the form of film at a position opposed to the electrode in the ink reservoir chamber, the erroneous detection results, that is, the existence of the ink is detected despite the fact that it does not exist.
The electrostatic capacity provided by the capacitive coupling described above generally changes with the opposing area retained second electrode and the ink, the distance between the second electrode and the ink or the like, and therefore, by regulating these factors, the electrostatic capacity is fundamentally stabilized so that time constant of the detection system for the detection of the ink remaining amount. In the case that plurality of ink reservoir chambers as in an ink jet recording apparatus for color recording or the like, the electrostatic capacity changes with the amount of the ink in the adjacent ink reservoir chamber, and therefore, the time constant of the detection system is influenced. The change of the time constant causes change of the gain of detection signal so that detection accuracy of the ink remaining amount is deteriorated.
Accordingly, it is a principal object of the present invention to provide a liquid supplying system and an ink container usable with the system which is usable with the ink container disclosed in EP0738605 and/or EP0581531, and into which the presence or absence of the ink in the ink container can be easily and assuredly detected so that spindle liquid supply is carried out.
It is another object of the present invention to provide a liquid supplying system and a liquid supply container in which a plurality of liquid containing chambers are juxtaposed, the remaining amount of the liquid in the liquid containing chambers are detected with high accuracy so that ink can be supplied stably, in addition to the first object or solely.
It is a further object of the present invention to provide a liquid supplying system and a liquid supply container in which the amount of the remaining liquid can be detected with high accuracy so that liquid can be supply stably, in addition to the first or second object or solely.
According to a first aspect of the present invention, there is provided a liquid supply system comprising: a liquid supply container provided with a liquid supply portion for supplying liquid to outside; detecting means for detecting presence or absence of the liquid in said liquid supply container, using an electrostatic capacity between the liquid in said liquid supply container and said electrode; wherein said electrode is disposed to be parallel with and spaced from a bottom surface of said liquid supply container, and the bottom surface is inclined relative to a horizontal plane from one end to another end of said liquid supply container, and has a connecting portion at a lower side end.
According to this aspect, the bottom surface of the liquid supply container is inclined relative to the horizontal plan, and the connecting portion is provided at a lower end, and then if the amount of the remaining liquid in the liquid containing portion is lower than the inclined surface, the area of the ink opposed to the electrode decreases with reduction of the liquid. With this, the electrostatic capacity detected by the detecting means decreases so that reduction of the amount of the remaining liquid can be assuredly detected.
The present invention provides a liquid supply system comprising: a negative pressure producing member accommodating chamber accommodating therein a negative pressure producing member and having a liquid supply portion for supplying liquid to outside; a liquid supply container connected with said negative pressure producing member accommodating chamber through a connecting portion and having a liquid reservoir portion which defines a substantially sealed space except for the connecting portion; an electrode extended parallel with a bottom surface of said liquid supply container, provided at least below said liquid supply container; detecting means for detecting an amount of the remaining liquid in said liquid containing portion on the basis of an electrostatic capacity between said electrode and the liquid in the liquid containing portion, wherein a configuration of said liquid reservoir portion is substantially similar to an inner configuration of said liquid supply container, and is capable of providing a negative pressure corresponding to deformation of the part corresponding to the bottom surface portion of said liquid supply container.
According to this system, the liquid containing portion deforms inwardly during consumption of the liquid from the liquid supply portion so that balance between the supply negative pressure producing member accommodating chamber and the ink supply is provided, the deformation occurs in the bottom surface of the liquid containing portion. Therefore, the remaining amount in the liquid containing portion reaches the bottom portion of the liquid containing portion, the area of the liquid opposed to the electrode decreases, the reduction of the amount of the remaining liquid can be easily and assuredly detected by detecting the change.
According to a second aspect of the present invention, there is provided a liquid supply system comprising a plurality of such liquid supply containers each having the liquid supply portion, wherein amounts of the remaining liquid in said liquid supply container is detected on the basis of impedances between the liquids and the electrode; wherein said liquid supply containers are disposed adjacent to one another, and each of said liquid supply containers has a side wall having a thickness which is smaller than a thickness of the bottom wall opposed to said electrode.
The inventors have particularly noted the electrostatic capacity between adjacent liquid containers when the remaining amount of the liquid in the liquid container is detected.
According to this aspect, the amount of the remaining liquid in the liquid supply container can be detected by detecting the change of the impedance between the electrode and the liquid in the liquid supply container (liquid containing portion). The thickness of the wall of the liquid supply container (liquid containing portion) is such that thickness of the side wall opposing to the adjacent liquid supply container is larger than a thickness of the bottom wall opposed to the electrode, and therefore, the influence of the electrostatic capacity produced between the adjacent liquid supply containers can be suppressed so that remaining amount of the liquid in the liquid supply container intended can be detected with high accuracy.
According to a third aspect of the present invention, there is provided a liquid supply system comprising a liquid supply container having a liquid supply portion for supplying liquid to outside; an electrode, disposed below said liquid supply container, for detecting an amount of the remaining liquid in inner on the basis of an impedance between the liquid and the electrode; a separating structure, provided in a region of said liquid supply container at a liquid supply portion side beyond a portion opposed the electrode, for separating the liquid in a region opposed to said electrode from a liquid supply portion side when a remaining amount of the liquid in said liquid supply container is a predetermined amount to be detected.
According to this aspect of the present invention, the change of the impedance between the electrode and the liquid in the liquid supply container (liquid containing portion), by which amount of the remaining liquid is detected. Here, the bottom wall of the liquid supply container (liquid containing portion) is provided with a separating structure, and therefore, when the remaining amount of the liquid in the liquid supply container, the liquid in the region opposed to the electrode is assuredly separated from the connecting portion (liquid discharge portion) side even if the liquid remains in the form of film on the bottom wall of the liquid supply container. Accordingly, the electrical circuit gained liquid and the electrode through the bottom wall of the liquid supply container is separated with the result of increased impedance. By detecting the event, the reduction of the amount of the remaining liquid in the liquid supply container can be detected.
The separating structure may be a protection extended in an entire area in the direction crossing with the direction toward the liquid discharge portion from the region opposing to the electrode, or it may be a step. The projection may include a first surface at a liquid discharging side and a second surface opposed to said electrode, and wherein an angle of the first surface relative to a horizontal plane in use is larger than an angle of the second surface relative to a horizontal plane. With this, the liquid separated by the projection can move toward the liquid discharge portion easily, whereas it is not easily moved toward the electrode opposing side.
The liquid supply container may be provided with recess. With this, the correct positioning of the liquid supply container is accomplished relative to the holder having a projection corresponding to the recess.
The present invention provides a liquid supply container per se.
The present invention provides a liquid container comprising: a liquid containing portion for accommodating liquid; a liquid discharge portion for discharging the liquid to outside; wherein said liquid supply container is provided with a bottom surface which is opposed to an electrode disposed below said liquid supply container, for detecting remaining amount of the liquid in said liquid containing portion on the basis of an electrostatic capacity between said electrode and the liquid.
The present invention provides a liquid supply container comprising: a plurality of liquid containing portions for accommodating liquid; a liquid discharge portions for discharging the liquid to outside; wherein said liquid containing portions are disposed adjacent to one another; wherein said liquid containing portion is provided with a bottom wall to which an electrode for detecting a remaining amount of the liquid in said liquid containing portion on the basis of an impedance between the liquid and said electrode; wherein said liquid containing portion includes a side wall opposed to the liquid containing portion adjacent thereto, said side walls having a thickness larger than that of said bottom wall.
The present invention provides a liquid container comprising: a liquid containing portion for accommodating liquid; a liquid discharge portion for discharging the liquid to outside; wherein said liquid containing portion is provided with a bottom wall to which an electrode for detecting a remaining amount of the liquid in said liquid containing portion on the basis of an impedance between the liquid and said electrode; a separating structure, provided in a region of said liquid supply container at a liquid supply portion side beyond a portion opposed the electrode, for separating the liquid in a region opposed to said electrode from a liquid supply portion side when a remaining amount of the liquid in said liquid supply container is a predetermined amount to be detected.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.